Following the idea of soaked almonds’ shells and hulls, I poured the coloured water in an old plexi glass box (100x100x5cm). I diluted the colored water just to get more quantity and placed the box against sunlight.
Also, I continued experimenting on the sketches. Some did not work (ink on paper, 80x70cm):
and some work as a basis for further experimentation (from left to right: (1) detail of third image above that I want to use for further experimentation on bigger scale, (2) 150×120 ):